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EPA looking to tighten SCR certification

The EPA has issued a draft guidance showing how it could tighten the requirements to certify engines and federal emissions standards

Jun 17, 2011

Given advances in the engineering of selective catalytic reduction (SCR) emission-control technology used on heavy-duty diesel engines, the Environmental Protection Agency (EPA) has issued a “draft guidance” detailing how it may tighten the requirements that must be met to certify these engines to Federal emissions standards.

EPA is requesting comments be filed on the guidance and that it will review the comments and provide final guidance on SCR at a future date. Notice of the draft guidance was published in the Federal Register for June 7th.

“The draft guidance contained in this document reflects the fact that manufacturers of heavy-duty engines and operators of trucks have gained significant experience in the design and use of SCR systems for these engines, and this experience should be

reflected in the certification process,” pointed out EPA.

The agency said, for example, that it recognizes that development of “even more robust sensors and inducements [to keep DEF levels correct] does not negate past approaches implemented pursuant to existing regulations. Rather, continual improvement is expected given the mounting experience with, and the maturing of, SCR technology, and the greater availability of DEF. As improved strategies and capabilities for proper SCR operation become feasible, EPA may guide their application to provide even further assurance that the technology is operating as intended on SCR-equipped engines”.

EPA added that it is very interested in receiving comments on four design criteria divided into these four categories within the draft guiidance: